Continued development of a new and promising nuclear magnetic resonance (NMR) method for measuring the topographic distribution of water in lung tissue is proposed. By control of externally applied static magnetic fields with small gradient components and radiofrequency (RF) electromagnetic fields, the spatial distribution of water protons and other hydrocarbons may be determined by detection of the associated NMR interactions. The proposed method is highly sensitive to and selective of water concentration, and therefore promises to provide the first quantitative noninvasive determination of relative and absolute water concentration in the lungs. It is expected to provide a powerful tool for physiologic study of lung edema and for clinical evaluation of disorders associated with altered lung density, whether due to edema (cardiogenic and noncardiogenic), to pulmonary vascular engorgement (left atrial hypertension), or to increased (pulmonary fibrosis) or decreased (emphysema) lung tissue volume. Topographic distributions of lung water (3-dimensions, 2-dimensional slices, or defined regions) and graphic distributions of lung water density with respect to lung volume, both obtained by NMR imaging techniques, will provide complementary information. It may be possible to identify useful mathematical descriptors of lung density versus lung volume curves. Normal and edematous isolated rat lungs (perfused and unperfused) and intact rats will be studied in a high spatial resolution (0.5 to 1.0 mm) imaging system with a high intensity (10,000 gauss) magnetic field. To improve the NMR imaging system for pulmonary applications, effects of respiratory motion on NMR images of lung water distribution will be identified and methods of minimizing errors in NMR images due to motion will be investigated. Methods to be investigated include shorter (less than 90 degrees) excitation pulses applied more often than once every T1, data collection synchronized with the respiratory cycle, and use of the selective irradiation method and/or spin echo method to reduce the data collection time. Pilot studies (previous grant) have demonstrated the feasibility of obtaining topographic NMR images of normal and edematous isolated rat lungs.